The present invention generally relates to memory devices for use with computers and other processing apparatuses. More particularly, this invention relates to Serial ATA (advanced technology attachment), or SATA, as an interface standard for non-volatile or permanent memory-based mass storage devices.
SATA is a computer bus interface for connecting mass storage devices, for example hard disk drives (HDDs) and optical drives, to a host bus adapter (host controller) of a computer. As with prior bus interfaces, the SATA interface comprises complementary connectors (female and male) adapted to connect to each other, one connector being mounted or otherwise connected to the drive and the other connected to a data cable over which data are transmitted to and from the drive. FIG. 1 represents a conventional SATA interface 10 adapted to solely transmit data to and from a drive (not shown) through a connector 12 and data cable 14, necessitating a second connection (not shown) for supplying power to the drive. The SATA interface 10 uses a simplified connectivity scheme compared to parallel ATA. The pin configuration is a staggered contact seven-pin connector with interspersed ground or shield contacts that discharge any electrostatic charges before data lines are connected. Two pairs of data lines provide differential signaling in each direction, that is, load and store are provided in full duplex fashion. Consequently, only four connector pins are necessary to transfer the data from the data cable 14 to the drive, and vice-versa.
One of the critical issues in the design of the SATA interface has been to provide enough rigidity for the interface so that the cables are securely attached to the data and power connector. This issue is of particular importance in view of the high-speed signaling used in SATA technology, starting at 1.5 Gbps in the first generation, 3.0 Gbps in the second current generation, and heading towards 6 Gbps for the third generation. Another issue is the avoidance of damage to a drive to which a SATA interface is connected in the event that the connection is so secure that excessive stresses can be exerted through the data cable on the connector attached to the drive. Current connector-cable configurations used with SATA interface connectors of the type shown in FIG. 1 typically present a compromise between the two extremes of an excessively loose and an excessively tight connection to a drive. If too loose, the SATA connector may not be sufficiently secure to avoid inadvertent disconnections, and may also allow misalignments with the drive's connector. The result can lead to signal and potential data loss or even system damage. On the other hand, if the SATA connector is too tightly connected to the drive's connector, there is a risk that excessive mechanical stresses can damage the connector on the drive. This type of stress can occur in situations of an open case, or simply during maintenance or drive swapping in which case the drive must be disconnected from the cable. Particularly in the case of hot-swap enabled devices, that is, devices that can be inserted and removed from a computer without shutting the system down, an excessively tight connection can result in undue mechanical stress on the connector or the printed circuit board to which it is attached.
To address the above issues, SATA interfaces have been designed to allow the cable connector to disengage from the drive connector prior to the mechanical stability of the drive connector being compromised. For this purpose, several iterations of cable designs have been devised over the past that have incorporated some type of clip adapted to engage the drive connector. These designs have partially addressed the problem of wear and loose contacts, though at the risk of incurring damage to the electrical connectivity between the drive and its connector, particularly the solder connections.
A different possible approach to the above is offered by the smaller form factor of the standard 2.5-inch drive. Whereas a SATA connector that engages the housing of a 3.5-inch drive (typically about 20 mm height) would be extremely bulky, the form factor of a 2.5-inch drive typically uses a height of about 9 mm, which allows for a slim-line connector with enough sturdiness to securely engage with the drive housing without adding additional mechanical strain on the connector, including the data and power connections between the connector and the drive.
Serial Attached SCSI (SAS) is another type of computer bus used to move data between computer mass storage devices, including hard drives and tape drives. FIG. 2 represents a SAS interface 20 that combines power and data connections in a single connector 22. The connector 22 has a conventional SAS form factor. Data and power cables 24 and 26 are separately coupled to the SAS connector 22 for transmitting both data and power to a drive through separate portions 28 and 30 of the connector 22 containing, respectively, data and power pins (not shown). The additional size and weight of the SAS connector 22 relative to the SATA connector 12 of FIG. 1 exacerbate the problems and compromises discussed above as being associated with SATA connectors.